Isosorbide Dinitrate, classified as a vasodilator, anti-anginal compound, is chemically known as 1,4:3,6-dianhydro-D-glucitol dinitrate; 1,4:3,6-dianhydrosorbitol 2,5-dinitrate; dinitrosorbide; sorbide dinitrate; and sorbide nitrate. It has a CAS number of 87-33-2. Isosorbide dinitrate has a chemical formula of C6H8N2O8, and a molecular weight of 236.1.
The chemical structure of isosorbide dinitrate is shown below:

Isosorbide dinitrate is a fine white to ivory-white odorless crystalline solid. It is sparingly soluble in water (1.0 g/900 ml); freely soluble in acetone, chloroform, alcohol and ether, and has a melting point of 70° C. Isosorbide dinitrate is a synthetic substance prepared from sorbitol. Diluted isosorbide dinitrate is a mixture of isosorbide dinitrate (usually 20-50%) with lactose, mannitol, or excipients added to minimize the risk of explosion. It may contain up to about 1% of a suitable stabilizer such as ammonium phosphate.
Isosorbide dinitrate is commercially available, for example, under the trade names DILATRATE®-SR (Schwarz Pharma, Milwaukee, Wis.); ISORDIL® and ISORDILR TITRADOSE® (Wyeth Laboratories Inc., Philadelphia, Pa.); and SORBITRATE® (Zeneca Pharmaceuticals, Wilmington, Del.). Isosorbide dinitrate is also commercially available under such trade names as Cedocard-5, Cedocard-10, Cedocard-20, Cedocard Retard, Cedocard IV (Tillotts, UK), Isoket, Isoket 10, Isoket 20, Isoket Retard, Isoket 0.1% (Schwartz, UK), Isordil, Isordil Tembids (Ayerst, UK), Sorbichew, Sorbitrate (Stuart, UK), Vascardin (Nicholas, UK), Soni-Slo (Lipha Rona, UK); Conducil, Corosorbide, Maycor, Sigillum, Surantol, Vasodilat (Argentina); Carvasin, Isotrate (Australia); Sorbidilat (Belgium); Coronex (Canada); Risordan (France); Cardis, Corovliss, IsoMack, Maycor, Nitrol, Nitrosorbon, Sorbidilat, Vermicet (Germany); Carvasin, Nitrosorbide, (Italy); Directan, Nitrol (Japan); Isorbid (Mexico); Sorbaugil (Norway, Sweeden); IsoMack, Myorexon, Sorbidilat (Switzerland); Iso-Bid, Iso-D, Isotrate, Sorbide, Sorquad, Vasotrate (USA).
Isosorbide dinitrate is used principally for management of ischaemic heart disease by reducing the number, duration and severity of episodes of angina pectoris. It is effective for angina (e.g., stable effort angina, mixed angina, unstable angina and vasospastic or variant angina). Isosorbide dinitrate is used in acute myocardial infarction in control of ischaemic pain, reduction of elevated blood pressure and in the treatment of pulmonary edema and congestive cardiac failure. It is also useful in the treatment of severe hypertension.
Therapeutic isosorbide dinitrate dosages for adults for relief of acute attacks of angina, generally range from about 2.5 mg to about 10 mg. For long term management of ischaemic heart disease dosing ranges from about 30 mg to about 240 mg per day. Starting doses for the treatment of angina pectoris may be about 2.5 mg to about 10 mg every 2 to 3 hours, with dosages gradually increased up to about 10 mg to about 40 mg every 6 hours.
Hydralazine (including its salts, such as hydralazine hydrochloride) is classified as a vasodilator, antihypertensive compound. Hydralazine, also known as 1-hydrazinophatalazine; has a CAS number of 86-54-4. Hydralazine hydrochloride, also known as 1-hydrazinophtalazine hydrochloride; has a CAS number of 304-20-1. Hydralazine has the chemical structure of C8H8N4, and hydralazine hydrochloride has the chemical structure of C8H8N4.HCl.
The chemical formula of hydralazine and hydralazine hydrochloride are shown below:

Hydralazine hydrochloride has a white to off-white substance color and is a crystalline powder. It is an odorless to almost odorless compound. It is soluble in water (1 in 25), slightly soluble in ethanol (1 in 500) and in methanol; practically insoluble in ether or chloroform. A 2% solution in water has a pH of about 3.5 to about 4.2.
Hydralazine hydrochloride is commercially available from, for example, Lederle Standard Products of Pearl River, N.Y. and Par Pharmaceuticals Inc. of Spring Valley, N.Y. Hydralazine hydrochloride is branded under several trade names, such as Alphapress, Apresolin, Apresolina, Apresoline, Dralzine, Hidralazina, Hydralazine Hydrochloride Tablets USP 23, Hydralazine Injection BP 1993, Hydralazine Tablets BP 1993, Hydrapress, Hyperphen, Ipolina, Lowpress, Nepresol, Novo-Hylazin, Rolazine, Slow-Apresoline, and Supress.
Hydralazine, including its pharmaceutically acceptable salt forms, e.g., hydralazine hydrochloride, is useful in the treatment of arterial hypertension (primary; malignant; pulmonary; pre-eclampsia and eclampsia), congestive heart failure, pulmonary hypertension in chronic obstructive pulmonary disease, and aortic regurgitation. Therapeutic dosages for adults range generally from about 10 mg four times a day for the first 2 to 4 days, increasing to about 25 mg 4 times a day for the remainder of the first week. For the subsequent weeks, dosages may be increased up to about 50 mg 4 times a day. For heart failure dosages may range up to about 800 mg daily or more.
Isosorbide dinitrate and hydralazine hydrochloride combinations, and/or like compounds, have been disclosed, for example, in U.S. Pat. No. 4,868,179 to Cohn for “Method of Reducing Mortality Associated with Congestive Heart Failure Using Hydralazine and Isosorbide Dinitrate”; U.S. Pat. No. 6,465,463 to Cohn et al. for “Methods of Treating and Preventing Congestive Heart Failure with Hydralazine Compounds and Isosorbide Dinitrate or Isosorbide Mononitrate”; U.S. Pat. No. 6,635,273 to Loscalzo et al. for “Methods of Treating Vascular Diseases Characterized by Nitric Oxide Insufficiency”; and United States Patent Application No. 2004/0204371 to Cohn et al. for “Kits of Hydralazine Compounds and Isosorbide Dintrate and/or Isosorbide Mononitrate”.
The combination of isosorbide dinitrate and hydralazine hydrochloride has been developed by Nitromed, Inc. of Lexington, Mass. under the trade name BiDil®. The combination has been reported to provide a synergistic therapeutic effect for patients over the individual use of each of the active agents. BiDil® is generally administered three times a day in dosages of isosorbide dinitrate/hydralazine hydrochloride, respectively from about 60/112.5 to about 120/225 mg.
The present invention relates to a composition for the controlled-release of a combination of isosorbide, including salts, derivatives and metabolites thereof, such as isosorbide dinitrate, (referred to herein as “isosorbide dinitrate”) and hydralazine, or salt or derivative thereof, such as hydralazine hydrochloride (referred to herein as “hydralazine hydrochloride”). In particular, the present invention relates to a composition that in operation delivers an active isosorbide dinitrate and hydralazine hydrochloride combination in a pulsatile or in a constant zero order release manner. The present invention further relates to solid oral dosage forms containing such a controlled release composition. The present invention is particularly applicable for multiparticulate formulations of a combination product for isosorbide dinitrate and hydralazine hydrochloride, providing a twice-a-day or once daily administration. In particular, the present invention provides immediate-release pellets and/or beads for isosorbide dinitrate and hydralazine hydrochloride, e.g., using powder layering technology or standard Glatt Wurster Process, and sustained-release pellets and/or beads for isosorbide dinitrate and hydralazine hydrochloride, e.g., using various polymers or combination of polymers to provide various release rates ranging from about 6 hours to about 12 hours or about 12 hours to about 24 hours with or without lag time. In one particularly preferred embodiment, these multiparticulates are encapsulated in a hard gelatin capsule to give an isosorbide dinitrate content of about 30 mg to about 120 mg and a hydralazine content of about 50 mg to about 250 mg ranging for about 12 hour to about 24 hour dosing. Representative proportions of the immediate release (IR) beads vary from about 10% to about 60%, with representative proportions of complementary sustained release (SR) beads varying from about 30% to about 90%. The IR/SR combination may be blended for ease of manufacture or may be individually dosed with capsules. Additionally, the multiparticulates manufactured can be tabletted using suitable excipients to give appropriate isosorbide dinitrate and hydralazine content, as stated above.